Two, well three, thoughts: someone mentioned picking up after yourselves. We quilters are usually covered with threads and they just seem to leave a trail behind us. They can sure wrap around the beater bar of a vacumn. I would ask the quilters to try to keep threads to the trash can and offer to vacumn before leaving.
The second thought is lighting. There may be enough ambiate lighting....you could check out the room. Usually a task light is needed. And lighting over the cutting and pressing stations may be needed.
As to electricity: one standard iron can use as much electricity as 60 Clover mini wand irons. There are non-electric ways to "press" seams such as a wall-paper breyer and Clover pressing sticks. These can get the seams going the right direction and then the project only needs pressing occasionally. (When I've been to retreat centers, they ask if there's anything we might need. It's always more electricity.) With all the irons, lights and machines, the circuits can get overloaded. (Let's see....on one hand-use the elctricity for sewing OR for crock pot? DUH.)
Here's #4: electric cords loosely draped across the floor can be a hazzard. Either plan to tape them down or throw a rubber mat over them.
I may think of more...........